The present invention relates to a method and apparatus for a printing system. More specifically, the invention relates to printer rolls and belts for printing systems.
Cross reference is made to the following application filed concurrently herewith Ser. No. 08/669,761 entitled xe2x80x9cLeveling Blade for Flow Coating Process for Manufacture of Polymeric Printer Roll and Belt Componentsxe2x80x9d by Patrick J. Finn et al.
The features of the present invention are useful in the printing arts and more particularly in electrophotographic printing. In the well-known process of electrophotographic printing, a charge retentive surface, typically known as a photoreceptor, is electrostatically charged, and then exposed to a light pattern of an original image to selectively discharge the surface in accordance therewith. The resulting pattern of charged and discharged areas on the photoreceptor form an electrostatic charge pattern, known as a latent image, conforming to the original image. The latent image is developed by contacting it with a finely divided electrostatically attractable powder known as xe2x80x9ctoner.xe2x80x9d Toner is held on the image areas by the electrostatic charge on the photoreceptor surface. Thus, a toner image is produced in conformity with a light image of the original being reproduced. The toner image may then be transferred to a substrate or support member (e.g., paper), and the image affixed thereto by fusing the toner image to the paper to form a permanent record of the image to be reproduced. Subsequent to development, excess toner left on the charge retentive surface is cleaned from the surface. The process is useful for light lens copying from an original or printing electronically generated or stored originals such as with a raster output scanner (ROS), where a charged surface may be imagewise discharged in a variety of ways.
Several components in the electrophotographic printing process described above are in the form of polymeric rolls and belts. Fusing rolls which are used to fix the toner image on a substrate represent a component that is typically in the form of polymeric rolls and belts. Also included among these components are bias charge rolls (BCRs) and bias transfer rolls (BTRs) which electrostatically charge the photoreceptor. Other forms of polymeric rolls and belts include the pressure or backup roll used with a fusing roll to fix the toner image on a substrate. Another form of a polymeric rolls and belts are donor rolls which transfer oil to the fuser roll that assists in releasing the toner from the fuser roll. A further form of polymeric rolls and belts include intermediate transfer rolls and belts that transfer developed images. Another form of polymeric rolls and belts include photoconductive belts and rolls. Other forms of polymeric rolls and belts include those belts and rolls used in Hybrid Scavangeless Development (HSD) as disclosed in U.S. Pat. No. 4,868,600 to Hays et al. and in U.S. Pat. No. 5,172,170 to Hays et al., the relevant portions thereof incorporated herein by reference. All of these a polymeric rolls and belts are typically manufactured by spraying or by dipping
A particularly difficult polymeric rolls and belts to manufacture are fuser rolls and belts. The elevated temperatures and pressures of these rolls and the accurate size and finish requirements necessary to insure proper copy quality make their manufacture difficult.
The fusing of the toner image to the paper to form a permanent record of the image is an important part of the xerographic process. Fusing of the toner image is typically done by heat fixation. The heat fixation may be in the form of radiation, conduction, convection or induction. Most modem xerographic processes utilize conduction heating of the toner image to adhere the image to the paper. This is performed by a fusing roll in contact with the toner image. A fusing roll is placed in rolling contact with a backup roll forming a nip therebetween. The paper having the toner image laying thereon is fed between the rolls through the nip. Heat from the fusing roll together with the pressure within the nip between the fuser roll and the backup roll serve to fuse the image to the paper. Heat is typically applied internally within the roll and is transferred through the substrate of the roll onto the periphery of the roll and onto the paper. The rolls typically include a thermally conductive substrate with a surface layer which is also thermally conductive. To assure uniform transfer of the image onto the paper, typically the fuser roll coating is conformable to the paper. For example, the coating may be in the form of a rubber or polymer material, e.g. a fluoroelastomer coating.
Applying fluoroelastomer and other rubber type coatings to fuser roll substrates is fraught with many problems. The coating may be applied to the substrate by two typical methods which are dipping of the substrate into a bath of coating solution or spraying the periphery of the substrate with the coating material.
Spraying is the typical method for the manufacture of fluoroelastomer rollers. The spraying process is very slow and costly. Also, the spraying process requires having the coating solution in a form that is very volatile including many volatile organic chemicals. Further, the spraying process is very prone to air pockets or pits forming in the coating. These pits or air pockets in the coating material of the roll result in improper fusing and poor image quality. Because of the nature of the spray process, much of the coating material is lost in the atmosphere requiring an excess amount of the expensive coating material utilized. Also, the loss of the volatile chemicals result in expensive containment costs for systems to contain the volatile chemicals as well as disposal costs of these materials.
Recently a process has been attempted to drip material over a horizontally rotating cylinder. With this process a portion of the material adheres to the cylinder and the remainder drips from the cylinder. The amount of material added to the roll is not precisely controlled as the percentage that adheres varies as parameters change over the production run. Also the material forms a wavy surface where the material is poured.
This invention is intended to alleviate at least some of the above-mentioned problems for at least some of the several components in the electrophotographic printing process described above which are in the form of polymeric rolls and belts.
The following disclosures may be relevant to various aspects of the present invention:
U.S. Pat. No. 5,455.077 discloses a crowned resilient roll of continuously increasing diameter from the axially opposed ends. The resilient roll includes a columnar roll body formed of a resilient material and a coating layer formed on an outer circumferential surface of the roll body. The coating is applied to a rotating body with the speed of the rotating body being decreased in the middle of the roll.
U.S. Pat. No. 5,448,342 discloses a coated transport roll including a core with a coating of charge transporting molecules and an oxidizing agent dispersed in a resin. The transporting molecules includes aryldiamine molecules.
U.S. Pat. No. 5,416,566 discloses a magnetic roll assembly including a rotatable nonconductive shell surrounding a magnetic member to prevent eddy currents during rotation. The substrate has an elastomer coating formed over it.
U.S. Pat. No. 5,386,277 discloses a coated toner transport roller including a core with a coating of an oxidized polyether carbonate.
U.S. Pat. No. 5,378,525 discloses a crowned resilient roll of continuously increasing diameter from the axially opposed ends. The resilient roll includes a columnar roll body formed of a resilient material and a coating layer formed on an outer circumferential surface of the roll body. A protective layer of N-methoxymethlated nylon is applied to the coating.
U.S. Pat. No. 5,300,339 discloses a coated toner transport roll containing a core with a coating of transporting molecules dispersed in a binder and an oxidizing agent of ferric chloride and/or trifluoroacetaic acid. The coating possesses a relaxation time of from about 0,0099 millisecond to about 3.5 milliseconds and a residual voltage of from about 1 to about 10 volts.
U.S. Pat. No. 5,245,392 discloses a donor roll for conveying toner in a development system. The roll includes a core of an electrically conductive material such as aluminum. The core is coated with a resin, for example a phenolic, to obtain a suitable conductivity to facilitate a discharge time constant of less than 300 microseconds.
U.S. Pat. No. 5,177,538 discloses a donor roll for a printer formed by mixing resin particles with conductive particles and subsequently extruding or centrifugal casting the mixture into a cylindrical shell. The shell is cut to the desired length and journals are attached to each end of the shell. The resin particles are thermoset particles preferably phenolic resin particles, and the conductive particles are preferably graphite particles.
U.S. Pat. No. 4,891,081 discloses a method of molding and a foamed resin molding in which a skin layer is formed by pressing an expandable film against and into conformity with cavity walls of a mold or a bag-like cover member by foaming pressure of a foamable resin and a formed resin body molded concurrently and integrally under the skin layer.
U.S. Pat. No. 4,278,733 discloses a laminate product and method of making the same involving a base material such as cellulose fibrous materials impregnated with a cured mixture of aniline, phenol, formaldehyde and epoxy resin, which laminate has electrical and mechanical properties with improved heat resistance over previous materials.
U.S. Pat. No. 4,034,709 discloses a developer roll for a xerographic copier. The roll includes a tubular member made a non-magnetic metal for example aluminum. The roll is coated with a layer of styrene-butadiene. Magnets are disposed in the interior of the tubular member.
U.S. Pat. No. 3,616,046 discloses a laminated product possessing good physical and electrical properties made with an impregnating resin which is a reaction product of aniline, phenol and formaldehyde. These resins impart unusually good electrical and physical properties to the laminated product and are sufficiently water soluble as to allow their water content to be adjusted for direct, one stage impregnation of cellulose fiber materials such as paper.
xe2x80x9cNew Roll-Covering Process Uses RTV Siliconesxe2x80x9d, discloses a technique for covering metal rolls with silicone rubber. To produce the coating a prepared mandrel is centered and locked in position on a standard metal working lathe. The elastomer is applied to the mandrel by pumping from a pail through a trough onto the mandrel.
In accordance with one aspect of the present invention, there is provided a polymeric printing member for use in a printing machine. The polymeric printing member includes a substrate and a coating applied to the substrate. The coating is applied to the substrate by rotating the substrate about its longitudinal axis and applying the coating from an applicator to the substrate in a spiral pattern in a controlled amount so that substantially all the coating that exits the applicator adheres to said substrate.
In accordance with another aspect of the present invention, there is provided a printing machine including a polymeric printing member. The roll includes a substrate and a coating applied to the substrate. The coating is applied to the substrate by rotating the substrate about a longitudinal axis thereof and applying the coating from an applicator to the substrate in a spiral pattern in a controlled amount so that substantially all the coating that exits the applicator adheres to the substrate.
In accordance with a further aspect of the present invention, there is provided a method for manufacturing a polymeric printing member for use in a printing machine. The method includes the steps providing a generally cylindrically shaped substrate, rotating the substrate about a longitudinal axis thereof, and applying the coating from an applicator to the substrate in a controlled amount so that substantially all the coating that exits the applicator adheres to the substrate.